PHYSICAL-MECHANISMS OF THE TEMPERATURE ANOMALIES EVOLUTION IN THE MIDDLE LATITUDE OCEAN MIXED-LAYER

The sea surface temperature anomalies (SSTA) with time scales from day to several months are studied for 50-months period in the North Atlantic storm track zone (53-degrees-N, 35.5-degrees-W). The life times of SSTA are 5-6 days (50% events), 9 - 11 (15%), 15 (7%) and 20 - 25 days (10%). The SSTA amplitudes coincide with interannual anomalies. The SSTA amplitudes (not greater then 2-degrees-C) are modulated by the mixed layer (ML) depth seasonal evolution. The main cause of the SSTA changes is the ocean surface heat budget synoptic anomalies (60% total SSTA change). The other causes of the SSTA changes are interaction of ML depth anomalies with the mean ML temperature (19%), the mean ML temperature advection by anomalous wind-driven currents (14%) and the entrainment anomalies at the lower ML boundary (7%). The roles of these SSTA evolution factors may change. The ML interacts with atmosphere by its upper part in winter and by its total volume during the warm part of the year at denoted time scales.